assertThat(immutableGraph).isNotEqualTo(mutableGraph);
  }

  @Test
  public void copyOfImmutableGraph_optimized() {
    Graph<String> graph1 = ImmutableGraph.copyOf(GraphBuilder.directed().<String>build());
    Graph<String> graph2 = ImmutableGraph.copyOf(graph1);

    assertThat(graph2).isSameInstanceAs(graph1);
  }

  @Test
  public void immutableGraphBuilder_appliesGraphBuilderConfig() {
    ImmutableGraph<String> emptyGraph =

    assertThat(immutableGraph).isNotEqualTo(mutableGraph);
  }

  @Test
  public void copyOfImmutableGraph_optimized() {
    Graph<String> graph1 = ImmutableGraph.copyOf(GraphBuilder.directed().<String>build());
    Graph<String> graph2 = ImmutableGraph.copyOf(graph1);

    assertThat(graph2).isSameInstanceAs(graph1);
  }

  @Test
  public void immutableGraphBuilder_appliesGraphBuilderConfig() {
    ImmutableGraph<String> emptyGraph =

 * terms</a>):
 *
 * <ul>
 *   <li>directed graphs
 *   <li>undirected graphs
 *   <li>graphs that do/don't allow self-loops
 *   <li>graphs whose nodes/edges are insertion-ordered, sorted, or unordered
 *   <li>graphs whose edges have associated values
 * </ul>
 *
 * <p>{@code ValueGraph}, as a subtype of {@code Graph}, explicitly does not support parallel edges,

  }

  @Test
  public void copyOfImmutableValueGraph_optimized() {
    ValueGraph<String, Integer> graph1 =
        ImmutableValueGraph.copyOf(ValueGraphBuilder.directed().<String, Integer>build());
    ValueGraph<String, Integer> graph2 = ImmutableValueGraph.copyOf(graph1);

    assertThat(graph2).isSameInstanceAs(graph1);
  }

  @Test
  public void incidentEdgeOrder_stable() {

 *
 * <h3>Usage</h3>
 *
 * Given an algorithm, for example:
 *
 * <pre>{@code
 * public <N> someGraphAlgorithm(N startNode, SuccessorsFunction<N> successorsFunction);
 * }</pre>
 *
 * you will invoke it depending on the graph representation you're using.
 *
 * <p>If you have an instance of one of the primary {@code common.graph} types ({@link Graph},
 * {@link ValueGraph}, and {@link Network}):

  }

  static void assertStronglyEquivalent(Graph<?> graphA, Graph<?> graphB) {
    // Properties not covered by equals()
    assertThat(graphA.allowsSelfLoops()).isEqualTo(graphB.allowsSelfLoops());
    assertThat(graphA.nodeOrder()).isEqualTo(graphB.nodeOrder());

    assertThat(graphA).isEqualTo(graphB);
  }

  static void assertStronglyEquivalent(ValueGraph<?, ?> graphA, ValueGraph<?, ?> graphB) {
    // Properties not covered by equals()

 *
 * <h3>Usage</h3>
 *
 * Given an algorithm, for example:
 *
 * <pre>{@code
 * public <N> someGraphAlgorithm(N startNode, PredecessorsFunction<N> predecessorsFunction);
 * }</pre>
 *
 * you will invoke it depending on the graph representation you're using.
 *
 * <p>If you have an instance of one of the primary {@code common.graph} types ({@link Graph},
 * {@link ValueGraph}, and {@link Network}):

 *
 * <h3>Usage</h3>
 *
 * Given an algorithm, for example:
 *
 * <pre>{@code
 * public <N> someGraphAlgorithm(N startNode, SuccessorsFunction<N> successorsFunction);
 * }</pre>
 *
 * you will invoke it depending on the graph representation you're using.
 *
 * <p>If you have an instance of one of the primary {@code common.graph} types ({@link Graph},
 * {@link ValueGraph}, and {@link Network}):

    /**
     * Construct a new value source, using the supplied object as the root from
     * which to start, and using expressions split at the dot ('.') to navigate
     * the object graph beneath this root.
     * @param root the root of the graph.
     */
    public ObjectBasedValueSource(Object root) {
        super(true);
        this.root = root;
    }

    /**

  @SuppressWarnings("Immutable") // The backing graph must be immutable.
  private final BaseGraph<N> backingGraph;

  ImmutableGraph(BaseGraph<N> backingGraph) {
    this.backingGraph = backingGraph;
  }

  /** Returns an immutable copy of {@code graph}. */
  public static <N> ImmutableGraph<N> copyOf(Graph<N> graph) {
    return (graph instanceof ImmutableGraph)
        ? (ImmutableGraph<N>) graph
        : new ImmutableGraph<N>(